When using a high-volume velocity fan for positive pressure ventilation, it should be placed how far outside the ventilation opening?

The correct distance for placing a high-volume velocity fan for positive pressure ventilation is typically 4-10 feet outside the ventilation opening. This distance is optimal because it allows the fan to effectively push air into the structure while minimizing the chances of disrupting the airflow patterns that are critical for maximizing ventilation effectiveness.

Positioning the fan too close can cause turbulent airflow, which may decrease the efficiency of air distribution within the space being ventilated. Conversely, placing it too far away might reduce the velocity and volume of air entering the area, limiting the positive pressure effect that is necessary for maintaining safe and effective ventilation. The chosen range of 4-10 feet strikes a balance between airflow efficiency and effectiveness, ensuring that the air is moved uniformly into the structure to manage smoke, heat, and toxic gases.